Ulster strongman Stephen Ferris last night threw down a Rugby World Cup gauntlet to Saturday’s quarter-final opponents Wales by insisting Ireland's back row is capable of mixing it with anyone.

He warned: “The way we're playing at the moment we fear no-one. All the focus is on doing a job on these boys.”

Improving Wales are no pushovers but Ferris is determined to present their toughest test.

Ferris, Sean O'Brien and Jamie Heaslip have formed the tournament's most effective partnership, though Wales and New Zealand are pushing them close.

There are few more destructive ball carriers than Ferris and O'Brien, the flankers whose physicality has identified them as Ireland's outstanding players.

Number eight Heaslip has shown a remarkable appetite for work and is the only member of the squad to have played every minute of all four pool matches.

“We fancy ourselves against any back row at the World Cup. Given the way we're playing we'd rate ourselves against anyone,” said Ferris as the Ireland squad landed in Wellington to prepare for their date with destiny and a possible first semi-final appearance.

Ferris added: “It's great being a part of this unit. Sean has been fantastic. The Italy game was only the second time I've started with him. Every time he carries the ball you're looking to run off his shoulder because you know he'll break the first tackle.

“Against Italy he showed the world what he's made of. Sean thinks the same of me and we both think the same of Jamie. We seem to be clicking very well and sharing the workload. The balance is good and it's worked well so far.

“Coming into the World Cup we talked about taking it game by game and that's what we've done.

“We need to approach Wales with the same attitude — the only thing that matters is beating them.”

Ferris continued: “Wales are playing some good stuff at the moment. We watched them before we played Italy.

“They looked very silky and it will be another massive contest for us. But the way we're playing at the moment we can beat anyone.

“Over the last couple of years we've been capable of raising our game — just look at the 2009 Grand Slam, beating England in March and then Australia here.

“Every week it's getting bigger and bigger. The prize for beating Wales is massive as it will mean we're here to the end of the tournament.

“All the focus will be on doing a job on these boys.”

Ireland lost all four warm-up internationals yet have so far proved one of the success stories of the World Cup, prompting Ferris to draw similarities with England four years ago.

“Australia was a game we knew we could win if we played to our potential, but there's more in the tank,” said the Lions flanker.

“We feel as though we're progressing game by game. Against Italy we showed we can be clinical and our decision making throughout was exceptional.

“The way we're playing, we have to be ambitious. England four years ago didn't have a good record coming into the competition but reached the final. Hopefully we can go one step further.”

The participation of Ferris’s Ulster team-mate Rory Best against Wales on Saturday remained in serious doubt last night.

Ulster hooker Best sprained the AC join in his right shoulder during Sunday's decisive 36-6 victory over Italy at Otago Stadium and is receiving treatment.

A replacement for the 29-year-old Co Armagh ace, who has been playing the best rugby of his Ireland career, has yet to be summoned and a clearer picture over his condition will emerge today.

“Rory's doubtful for the weekend but we haven't written him off just yet,” said manager Paul McNaughton. Ireland have already lost one hooker during the World Cup after Jerry Flannery returned home two and a half weeks ago with a calf problem.

“Rory has been playing fantastic rugby and it would be a blow if he's not available,” added McNaughton. “But we have two hookers out here and back up in Ireland if we need it. Other teams have had injury problems and we must get on with it.”

McNaughton revealed prop Cian Healy has been interviewed about an attempted eye gouge by Italy hooker Leonardo Ghiraldini during Sunday’s first half.

South Africa's Craig Joubert will take charge of Saturday's Ireland v Wales showdown.

England's quarter-final against France will be refereed by Steve Walsh.

The following day, Welsh official Nigel Owens will be the man in the middle for the All Blacks' clash with Argentina at Auckland's Eden Park.

New Zealand official Bryce Lawrence will whistle South Africa's highly-anticipated appointment with Australia.